Capacitors that have a built in safety mechanism may be useful for a variety of applications, such as for hybrid and all electric vehicles. In the event of a crash of such a vehicle, a charged capacitor may represent a significant electrical hazard to first responders as a typical capacitor bank uses 1000 mF of capacitance at a voltage of up to 2000 V. No current capacitor technology exists to drain the capacitor charge in a controlled way in the event of a crash.
Due to their electronic and optoelectronic properties, conjugated polymers, such as poly(p-phenylenevinylene) (PPV), are widely used in photovoltaics, organic light emitting diodes, and organic transistors. See C. Li et al., Chem. Rev. 110, 6817 (2010); A. C. Grimsdale et al., Chem. Rev. 109, 897 (2009), and L.-L. Chua et al., Nature 434, 194 (2005). Conjugated polymers, including PPV, tend to be highly insoluble in common solvents, which is a limiting factor for processing these materials into devices. One strategy to overcome the limited solubility of PPV is to create a non-conjugated soluble precursor polymer that can be integrated into a device; the material is then heated to high temperatures eliminating the leaving groups and conjugating the polymer backbone (forming PPV). While precursor routes have enabled the processing of highly insoluble precursor polymers, the associated electronic change in a polymer going from a non-conjugated to a conjugated state has never been utilized for an application.
The present invention uses the temperature-induced conjugation of a precursor polymer as a means to disable a capacitor.